CVE-2019-17557Public exploitNetwork attack vector

Reflected XSS via incomplete HTML tag stripping

Published May 4, 2020 · Updated Aug 5, 2024

Reflected XSS in the Apache Syncope EndUser login page in 2.0.0 through 2.0.14 and 2.1.0 through 2.1.5 allows remote attackers to run JavaScript. The EndUser app.js handler strips only closed HTML tags from the successMessage URL parameter before passing the result to the notification renderer, so an unclosed tag survives and the browser repairs it into executable markup. Exploitation requires a victim to open a crafted EndUser URL; the injected script then runs in that site origin with the victim session's browser privileges.

CVSS severity5.4
Medium
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in the Apache Syncope EndUser login page in 2.0.0 through 2.0.14 and 2.1.0 through 2.1.5 allows remote attackers to run JavaScript. The EndUser app.js handler strips only closed HTML tags from the successMessage URL parameter before passing the result to the notification renderer, so an unclosed tag survives and the browser repairs it into executable markup. Exploitation requires a victim to open a crafted EndUser URL; the injected script then runs in that site origin with the victim session's browser privileges.

The record

CVE
CVE-2019-17557
Published
May 4, 2020
Updated
Aug 5, 2024
Vendor
The Apache Software Foundation
Product
Apache Syncope
Classifications
CWE-79, T1203
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. May 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Apache Syncope 2.0.X releases prior to 2.0.15, 2.1.X releases prior to 2.1.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

The Apache Software Foundation · Apache Syncopeversion=Apache Syncope 2.0.X releases prior to 2.0.15, 2.1.X releases prior to 2.1.6

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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